1. Field of the Invention
The present invention relates generally to a method preventing and/or treating viral infection in aquatic animals. More particularly, the invention provides new uses of trichoanguin protein in preventing and/or treating viral infection in aquatic animals.
2. Background of the Invention
Problem to be solved is that viral diseases to aquaculture is the primary obstacle to the growth of the aquaculture industry. For instance, shrimp culture industry, particularly in Asia, has been threatened by a viral syndrome, commonly known as the “white spot disease,” causing heavy mortality and financial losses. Several species of penaeid shrimps viz. Penaeus monodon, P. japonicus, P. chinensis, P. indicus, P. merguiensis and P. setiferus are known to be infected by this virus. The causative viral agent is known as different names in different countries, such as haematopoietic necrosis baculovirus (HHNBV), systemic ectodermal and mesodermal baculovirus (SEMBV), penaeid rod-shaped DNA virus (PRDV), white spot baculovirus (WSBV), Penaeus monodon non-occluded baculovirusII (PmNOBII), and Penaeus monodon non-occluded baculovirusIII (PmNOBIII). WSSV was found to target various tissues originating from both the mesoderm and ectoderm as evidenced by histopathological studies and in situ hybridization. Furthermore, the virus has also been detected in different organs/tissues including the reproductive organs of wild caught brooders of P. monodon indicating its vertical transmission. Besides white spot syndrome virus, there are about 20 shrimp diseases reported to be related to virus, such as infectious hypodermal hematopoietic necrosis virus (IHHNV), baculovirus penaei (BP), baculoviral midgut GI and necrosis virus (BMN), monodon baculovirus (MBV), hepatopan-creatic parvo-like virus (HPV), reo-like virus, Taura syndrome virus (TSV), and yellow head virus (YHV). Such diseases cannot be treated with normal aquiculture drugs.
Nervous necrosis virus (NNV), a pathogen found in many varieties of hatchery-reared marine fish, has caused mass mortality of such fish at their larval or juvenile stages. NNV belongs to the family Nodaviridae. Fish nodaviruses isolated from different species (such as SJNNV, BFNNV, JFNNV, TPNNV, RGNNV, GNNV etc.) are closely related to each other owing to the high similarity of the conserved region of their coat protein genes. NNV, also named as fish encephalitis virus (FEV) and piscine neuropathy nodavirus (PNN), is characterized by vacuolation of the nerve tissues. Viral Nervous Necrosis (VNN) disease has been found in many countries under various names such as viral fish encephalitis, fish encephalomyelitis, cardiac myopathy syndrome. The hosts of NNV include many species of marine fish; for example, parrotfish, sea bass, turbot, grouper, stripped jack, tiger puffer, berfin flounder, halibut, barramundi, and spotted wolffish.
Several strategies have been developed to control the viral infection in aquatic animals. U.S. Pat. No. 6,705,556 discloses a composition and method for inducing tolerance and/or immunity to white spot syndrome virus infections including inactivated white spot syndrome virus. U.S. Pat. No. 6,440,466 provides a composition useful as prophylactic and/or therapeutic agent for the management of white spot disease in aquatic animals, said composition containing effective amounts of extracts obtained from the plants, such as Lantena camera, Aegle marmelos, Ocimum sanctum, Mimosa pudica, Cynodon dactylon, Curcuma longa, and Allium sativum, optionally in combination with a pharmaceutically acceptable carrier, diluents or excipients. U.S. Pat. No. 5,401,727 provides a process for stimulating the immune system of the aquatic animals of the class Osteichthyes and subphylum Crustacea including administering an effective amount of a yeast cell wall glucan composed of glucopyranose units linked by predominately beta-1,3 glycosidic bonds, having at least one branch therefrom of glucopyranose units linked by beta-1,6 glycosidic bonds. U.S. Pat. No. 5,165,925 provides a method for immunizing fish against the infectious pancreatic necrosis virus (IPNV), including administering to susceptible fish a vaccine comprised of an IPNV polypeptide consisting essentially of a polypeptide from the viral A segment and including at least VP2. The polypeptide has been produced in a bacterial host by an expression vector compatible with the host, wherein the expression vector includes an inserted DNA sequence from said A segment of the viral DNA coding for the IPNV polypeptide in the vaccine. Such patents are incorporated herein by reference.